The present invention is for pharmaceutical compositions for transdermal delivery of N-[N-[5-[4-(aminoiminomethyl)phenyl-1-oxopentyl]-L-xcex1-aspartyl]-L-phenylalanine or its esters and their pharmaceutically acceptable salts which are useful as platelet aggregation inhibitors.
N-[N-[5-[4-(aminoiminomethyl)phenyl]-1-oxopentyl]-L-xcex1-aspartyl]-L-phenylalanine which is represented by the following formula 
or its esters and their pharmaceutically acceptable salts are known to be useful as platelet aggregation inhibitors. See International Publication W092/15607, published Sep. 17, 1992.
Platelets are cellular elements found in whole blood which also participate in blood coagulation. Fibrinogen binding to platelets is important to normal platelet function in the blood coagulation mechanism. When a blood vessel receives an injury, the platelets binding to fibrinogen will initiate aggregation and form a thrombus. Interaction of fibrinogen with platelets occurs through a membrane glycoprotein complex, known as gpIIb/IIIa; this is an important feature of the platelet function. Inhibitors of this interaction are useful in modulating platelet thrombus formation.
Initially, N-[N-[5-[4-(aminoiminomethyl)phenyl]-1-oxopentyl]-L-xcex1-aspartyl]-L-phenylalanine or its esters and their pharmaceutically acceptable salts were administered orally, parenterally, rectally or by inhalation spray. See International Publication W092/15607, published Sep. 17, 1992.
These prior conventional methods of administering drugs to patients, however, possess certain shortcomings.
The oral route of drug administration, for example, is inadequate for several reasons, even if the drug is administered to the patient at periodic intervals according to a well-defined schedule.
The rate of absorption of drug through the gastrointestinal tract is affected by both the contents in the tract and the passage of time as the drug travels through the small intestine. Therefore, such variables as whether the drug is administered before or after eating, and the type and quantity of food eaten, for example, high or low fat content, or whether the drug is administered before or after bowel movement, affect the rate of absorption of the drug which takes place in the small intestine.
Additionally, the time of passage of drug through the small intestine is affected by the rate of peristaltic contraction, adding further uncertainty.
Also important is the rate of circulation of blood to the small intestine, and the fact that many drugs administered by this route are rendered inactive by gastric acid, digestive enzymes of the gastrointestinal tract, or by liver, where the drug can be metabolized to an inactive product.
These factors make it difficult to achieve a desired time course of concentration of drug in the blood.
The most inevitable result of the oral administration of drugs through the gastrointestinal tract is that the level of drug in circulation surges to a peak level shortly after the time of drug administration, followed by a decline in drug concentration in the blood and body compartments.
The administration of drugs by injection likewise entails certain disadvantages. For example, very strict asepsis must be maintained in order to avoid infection of the blood, the vascular system and the heart. Drug administration by poor intravenous technique may result in perivascular injection, when that was not intended. The typical result of injection of a drug into the blood is a sudden rise in the blood concentration of the drug followed by an uncontrollable decline in drug concentration. Additionally, administration of drugs by injection is inconvenient and painful.
Other dosage forms for systemic administration of drugs, such as rectal suppositories and sublingual lozenges, also produce non-uniform levels of the therapeutic agent in circulation. These dosage forms require great patient cooperation and have low patient acceptability, resulting in decreased patient compliance with a prescribed drug regimen, which is the most common failure of drug therapy.
The present invention is a new form of administration of N-[N-[5-[4-(aminoiminomethyl)phenyl]-1-oxopentyl]-L-xcex1-aspartyl]-L-phenylalanine or its esters and their pharmaceutically acceptable salts into a transdermal pharmaceutical composition to achieve blood levels which are effective in the inhibition of platelet aggregation. Particularly interesting compounds which are representative of this above-described class of compounds are exemplified by
N-[N-[5-[4-(aminoiminomethyl)phenyl]-1-oxopentyl]-L-xcex1-aspartyl]-L-phenylalanine, hydrochloride;
N-[N-[5-[4-(aminoiminomethyl)phenyl]-1-oxopentyl]-L-xcex1-aspartyl]-L-phenylalanine, diethyl ester;
N-[N-[5-[4-(aminoiminomethyl)phenyl]-1-oxopentyl]-L-xcex1-aspartyl]-L-phenylalanine, dimethyl ester; and
N-[N-[5-[4-(aminoiminomethyl)phenyl]-1-oxopentyl]-L-xcex1-aspartyl]-L-phenylalanine, acetate.
Transdermal delivery of N-[N-[5-[4-(aminoiminomethyl)-phenyl]-1-oxopentyl]-L-xcex1-aspartyl]-L-phenylalanine or its esters and their pharmaceutically acceptable salts offers advantages over the other methods of delivery which were discussed above. An advantage is the ease of application over the intravenous or intramuscular delivery. This convenience of use offers the benefit of a lifestyle uninterrupted by hospital visits, which are needed when administering by other known methods. Administration by IV or intramuscular delivery has certain disadvantages of inadvertent needle sticks. Needle sticks have also been associated with the risk of secondary systemic infections. Transdermal delivery does provide the ability to deliver drugs directly to general circulation. Effective transdermal delivery affords a controlled, constant, zero-order release of active compound. Transdermal delivery is greatly advantageous in that it can be used in pediatric age groups, where IV or IM dosing is very difficult.
Another advantage of transdermal delivery is that the delivery of the active can be rapidly terminated by removing the patch. Other routes of delivery do not possess this most desirable advantage.
Recognizing that the outer layer of the skin, the epidermis, protects the area under the skin from penetration of foreign chemicals, various enhancing agents have been used to deliver drugs transdermally. Substances that help promote drug diffusion through the stratum corneum and epidermis are referred to as skin-penetration enhancers, accelerants, adjuvants and absorption promoters. B. Idson, Cosmetics and Toiletries, 95, 59 (1980) states that the factors affecting drug penetration and consequently in most cases, effectiveness, are complex. The vehicle that provides ideal conditions for one drug may prove unsatisfactory for another.
Various penetration enhancers are known to be useful in transdermal drug delivery. U.S. Pat. No. 4,863,970, U.S. Pat. No. 4,722,941, U.S. Pat. No. 4,931,283 and EP 351,897 disclose some representative penetration enhancers used in transdermal compositions and for topical administration.
The present invention provides a pharmaceutical formulation in the form of a transdermal delivery system comprised of N-[N-[5-[4-(aminoiminomethyl)phenyl]-1-oxopentyl]-L-xcex1-aspartyl]-L-phenylalanine or its esters and their pharmaceutically acceptable salts and a delivery solvent. Effective delivery solvents for the practice of this invention are exemplified by ethanol and n-methyl pyrrolidone.
It is the primary object of this invention to provide a pharmaceutical composition for transdermal delivery of N-[N-[5-[4-(aminoiminomethyl)phenyl]-1-oxopentyl]-L-xcex1-aspartyl]-L-phenylalanine or its esters and their pharmaceutically acceptable salts.
This invention encompasses pharmaceutical compositions for transdermal delivery of N-[N-[5-[4-(aminoiminomethyl)phenyl]-1-oxopentyl]-L-xcex1-aspartyl]-L-phenylalanine or its esters and their pharmaceutically acceptable salts. Particularly, this invention encompasses pharmaceutical compositions of
N-[N-[5-[4-(aminoiminomethyl)phenyl-1-oxopentyl]-L-xcex1-aspartyl]-L-phenylalanine, hydrochloride; and
N-[N-[5-[4-(aminoiminomethyl) phenyl]-1-oxopentyl]-L-xcex1-aspartyl]-L-phenylalanine, diethyl ester for transdermal delivery.
The term xe2x80x9cpharmaceutically acceptable saltxe2x80x9d refers to a salt prepared by acid-base reactions. Examples of pharmacologically acceptable salts include the hydrochloride, hydrobromide, hydroiodide, sulfate, phosphate, acetate, propionate, lactate, maleate, malate, succinate, and tartrate salts. All of these salts may be prepared by conventional means known by those of ordinary skill in the art. The most preferred salt is the hydrochloride.
The term xe2x80x9cestersxe2x80x9d refers to a radical having the following formula
xe2x80x94COOR
wherein the portion defined by R refers to a linear or branched saturated hydrocarbon group having 1 to 6 carbon atoms. Illustrative of such groups are methyl, ethyl, propyl, isopropyl and butyl.
The term xe2x80x9ccompositionxe2x80x9d as used herein means a product which results from the mixing or combining of more than one element or ingredient.
The term xe2x80x9cpharmaceutically-acceptable carrierxe2x80x9d as used herein means a pharmaceutically acceptable material, composition or vehicle, such as a liquid or solid filler, diluent, excipient, or solvent involved in carrying or transporting a chemical agent from one organ or portion of the body to another organ or portion of the body.
The term xe2x80x9ctransdermal deliveryxe2x80x9d as used herein means administration of the pharmaceutical composition topically to the skin wherein the active ingredient, or its pharmaceutically acceptable salts, will be percutaneously delivered in a therapeutically effective amount.
The term xe2x80x9cpenetration enhancersxe2x80x9d as used herein means compounds which enhance the percutaneous absorption of drugs. Selection of an effective penetration enhancer for a particular drug must be experimentally deduced. A penetration enhancer which works for one drug will not necessarily work for every other drug B. Idson, Cosmetics and Toiletries, 95, 59 (1980).
The term xe2x80x9cdelivery solventxe2x80x9d as used herein means a solvent in which the dissolution (dissolving of the active or compound into the solvent) is complete.
In the present invention N-[N-[5-[4-(aminoiminomethyl)-phenyl]-1-oxopentyl]-L-xcex1-aspartyl]-L-phenylalanine or its esters and their pharmaceutically acceptable salts are administered transdermally by topical application of N-[N-[5-[4-(aminoiminomethyl)phenyl]-1-oxopentyl]-L-xcex1-aspartyl]-L-phenylalanine or its esters and their pharmaceutically acceptable salts to the skin. More preferably these compounds can be administered in the form of a gel and covered with a suitable impenatrable membrane. The pharmaceutical compositions of the present invention can administer the N-[N-[5-[4-(aminoiminomethyl)phenyl]-1-oxopentyl]-L-xcex1-aspartyl3-L-phenylalanine or its esters and their pharmaceutically acceptable salts in admixture with a delivery solvent and suitable pharmaceutical diluents, carriers and excipients such as gelling agents, emollients, (i.e., allantoin and preservatives (i.e., parabens). Preferably N-[N-[5-[4-(aminoiminomethyl)-phenyl]-1-oxopentyl]-L-xcex1-aspartyl]-L-phenylalanine or its esters and their pharmaceutically acceptable salts are administered in admixture with a delivery solvent.
Delivery solvents suitable for the delivery of N-[N-[5-[4-(aminoiminomethyl)phenyl]-1-oxopentyl]-L-xcex1-aspartyl]-L-phenylalanine or its esters and their pharmaceutically acceptable salts are ethanol and N-methyl pyrrolidone. A preferred solvent is ethanol. The solvents are present in the range of 75 to 95%.
The practicality of administering a given drug percutaneously on a continuous basis depends upon the concentration of drug in the blood that is required to provide the desired pharmacologic effect, the degree to which the skin is permeable to the drug, and the amount of skin surface area that is available for drug administration.
The skin surface area which is available for drug administration, while theoretically being unlimited, is, for practical reasons, typically confined to a range Of from about 1 square centimeters to about 100 square centimeters. With the available skin surface area fixed within this range, the matter then narrows as to whether sufficient drug will pass through the defined skin surface area to provide the desired therapy. If it will, then it may not be difficult to effectively administer the drug percutaneously. If, however, the inherent permeability of the skin to the drug is so high or so low that too much or too little drug will pass through that area of skin, then the rate of administration of the drug to the skin must be controlled, or the permeability of the skin to the drug must be increased, as the case may be, to take percutaneous administration practical.
In order to inhibit platelets from aggregating, use of a non-toxic but therapeutically effective amount of a N-[N-[5-[4-(aminoiminomethyl)phenyl]-1-oxopentyl]-L-xcex1-aspartyl]-L-phenylalanine or its esters and their pharmaceutically acceptable salts is employed. The dose regimen for inhibiting platelet aggregation is selected in accordance with a variety of factors including the type, age, weight, sex and medical condition of the patient. A physician of ordinary skill can readily determine and prescribe an effective amount of the drug required to prevent or treat the progress of condition.
In order to achieve the desired therapeutic effect N-[N-[5-[4-(aminoiminomethyl)phenyl]-1-oxopentyl]-L-xcex1-aspartyl]-L-phenylalanine or its esters and their pharmaceutically acceptable salts parenterally, a dose of 10-50 mg/day is administered. N-[N-[[5-[4-(aminoiminomethyl)phenyl]-1-oxopentyl-L-xcex1-aspartyl]-L-phenylalanine or its esters and their pharmaceutically acceptable salts administered transdermally achieves similar plasma concentrations as the parenteral route of administration. In the preferred embodiment of the present invention N-[N-[5-[4-(aminoiminomethyl)phenyl]-1-oxopentyl]-L-xcex1-aspartyl]-L-phenylalanine or its esters and their pharmaceutically acceptable salts are administered in an amount of 100-500 mg/patch. In a more preferred embodiment of the present invention N-[N-[5-[4-aminoiminomethyl)phenyl]-1-oxopentyl]-L-xcex1-aspartyl]-L-phenylalanine or its esters and their pharmaceutically acceptable salts are delivered in an amount of 10-50 mg/day.
These doses were selected in order to achieve blood levels equivalent to that achieved with parenteral dosing. The required dose of active ingredient to be administered will vary with, amongst other factors, the severity of the condition being treated, and will depend on whether the treatment is remedial or prophylactic.
In order to administer the dose set out above the concentration of N-[N-[5-[4-aminoiminomethyl)phenyl]-1-oxopentyl]-L-xcex1-aspartyl]-L-phenylalanine or its esters and their pharmaceutically acceptable salts in the composition can be from 1 to 20 w/w. The concentrating of N-[N-[5-[4-(aminoiminomethyl)phenyl]-1-oxopentyl]-L-xcex1-aspartyl]-L-phenylalanine or its esters and their pharmaceutically acceptable salts is however preferably from 5 to 20 w/w.
The pharmaceutical compositions of the invention can be made, for example, by addition of a gel to a solution of the phenylamidine derivative. The solution gels and can be poured into a measuring-dispensing device. The gel can be extruded into sealable gel-tubes or syringes. The gel can be applied to the skin in a measured dose, dependent on the factors discussed above and covered with an impenetrable membrane.
Alternatively, the composition can be incorporated in a transdermal patch for delivery percutaneously. Methodology and design of transdermal patches for drug delivery are well known in the pharmaceutical art.